Aggravated parents shouldn’t get excited over the Moorpark Melodrama’s current “But Why Bump Off Barnaby?” No purple dinosaur gets offed in this comic murder mystery; you’d be thinking of Barney. In fact, the Melodrama’s first non-musical production in eight years is great fun.

We’re deep in Agatha Christie country here: The long-absent member of an aristocratic English family, Barnaby Folcey returns home at the request of patriarch Orion Leduc. Things aren’t all as they appear to be at the family manse, and before long, prodigal Barnaby has become the late Barnaby. Dying, he scrawls a message that (as it turns out) could implicate virtually anybody in the house. The other problem is that, while Barnaby had a motive for killing most of the others, none of the others had any perceptible motive to kill Barnaby.

There is a real mystery among the shenanigans, one that can be solved from clues revealed during the play (beyond that, we shall offer no further information). But much of the entertainment value comes from watching what director Steve Robertson and his cast do with Rick Abbot’s well-wrought, consistently amusing script–watch–for instance, Magnolia struggle with the guests’ heavy luggage, a gag that’s all but thrown away behind the main action.

There are no songs in “Barnaby,” but musical director Tim King supplies piano and synthesizer accompaniment throughout, and the cast gathers, along with Kevin McDonald and Amy Sullivan, for a post-Barnaby “salute to the good old days of vaudeville,” an approximately half-hour song and dance revue choreographed by Erin Appling.